Using straight SAE 30 or 40 wt. in a modern engine...

wavinwayne · Mar 9, 2005

What are the benefits/risks of using an SL or SM rated straight 30 or 40 weight oil for hot (85°-95°F) summer conditions in a modern gasoline engine?

I'm not really considering this.....it's just one of those what if's??? I've never really seen this discussed on here before.

haley10 · Mar 9, 2005

I use a good 30 wt. HD in my lawn mower. I think you will find that most very good 30wt. HD's will be SH due to the ZDDP levels. I doubt seeing SL or SM in a straight weight.

The mixed fleet oils are so good like Delvac 1300S, Delo 400 in 15W-40 that I would see no benefit to a straight 30 or 40 HD for a car or truck.

[ March 10, 2005, 02:15 PM: Message edited by: haley10 ]

JonS · Mar 9, 2005

At 90f, a 10w-30 has a cst of 104
at 90f, a sae 30 has a cst of 140
at 90f, a 15w-40 has a cst of 187
at 90f, a sae 40 has a cst of 226

k1xv · Mar 9, 2005

I looked over the spec sheets of single weight Rotella and Pennzoil LL, and they only meet SJ.

I would guess that, other than the additive levels, a single weight contains little or no viscosity index improver, so it may be preferable for engines that run hot and hard all day long, such as farm equipment.

wavinwayne · Mar 9, 2005

quote:

Originally posted by haley10:
...I doubt seeing SL or SM in a straight weight....

I found Castrol HD 30 & 40 SM rated. That's what made me ask my question.

http://www.castrol.com/liveassets/b.../local_assets/downloads/p,q/pds_HD30_HD40.pdf

haley10 · Mar 9, 2005

WavinWayne, I learn something new every day.

Might be good stuff if you have a new car and live in the Phillipines.

It would have been solid in my crankcase this morning and probably broke my oil pump.

I don't see any advantage over a 15W-40 hdeo.

[ March 10, 2005, 02:58 PM: Message edited by: haley10 ]

3putter · Mar 10, 2005

In my local Wal Mart, Castrol, Valvoline, Pennzoil, Havoline and SuperTech all have straight 30 weights with at least an SL rating.

The principal drawback is they are not rated for enhanced fuel economy. During warm weather, a straight 30W would run just fine in any vehicle where a 5 or 10w 30 is recommended. I used to run it in an 87 Buick I had with the First Generation 3.8L GM engine. It did great, and didn't use as much oil as a thinner all weather did. In theory you won't be subject to shearing because you don't have the heavy dose of Viscosity Improvers present like you do in a blended all weather oil.

bulwnkl · Mar 10, 2005

I farmed for a while in Yuma, AZ {fortunately, I only did so during the winter}. Almost all the farms there ran SAE 40 or even SAE 50 in their tractors during the summer there. Even passenger cars get lots of SAE 30 or SAE 40 there.

80-90F is frequently the overnight low in a place like Phoenix (I lived there year-round, too) during the summer. 115-120F or even 125F is a fairly common daytime high. IMHO, it is foolish to put 5W30 in an engine there. There's just no reason from any reasonable, realistic standpoint to have a 5W there during the summer. Garages are frequently noticeably hotter inside first thing in the morning than outside ambient, and the oil sump temps certainly don't go down much out over the asphalt in the parking lot while you're at work.

So, you use a straight-grade oil because the notion of start-up wear is completely absent from a practical point of view. And since all conditions point to much higher sump temperature equilibrium there, you strongly consider an SAE 40 or a 20W50.

Your high temperatures are not nearly that extreme, but the principle is similar. To me, there's no problem running a straight-grade oil in hot summer weather except the price at the pump. Since so many people drive far less fuel-efficient vehicles than they could, even that extra expense is dwarfed in comparison.

Alan · Mar 10, 2005

My old boss had an 89 Daytona that he only used straight 30W in,come winter or summer.It had 160k on it with nary an engine problem.

Transmission was a leaky sucker though.

Santo Fontana · Mar 10, 2005

Straight 30 and 40 weights are reccomended for severe service in my 2002 WRX, in the manual.

Camu Mahubah · Mar 10, 2005

I have used Napa 30w in my '77 New Yorker with 440 engine for two years now no problem. Although it is a pleasure machine for me and is usually never started in the mornings. I bought this boat in Nebraska from a farmer who says he never put anything but Conoco 30w or Quaker State 30w in her year round. Although I don't believe he drove her much in the winter.

When I bought her I drove her to the nearest quik lube and had Mobil 1 15w-50 installed, drove her to vegas and then back to Florida. At the end of this journey I decided to install Pennzoil 30w that the previous owner of my grove had left in a barn. And recently I have been pouring Napa 30w (valvoline) in. Though I only change the oil once or twice a year.

Audi Junkie · Mar 10, 2005

I cannot get Delo 10w-30 but SAE 30 is available. Too bad it says not for EGR-equipped vehicles.

John W. Colby · Mar 10, 2005

quote:

Originally posted by bulwnkl:
I farmed for a while in Yuma, AZ {fortunately, I only did so during the winter}. 80-90F is frequently the overnight low in a place like Phoenix (I lived there year-round, too) during the summer. 115-120F or even 125F is a fairly common daytime high.

I grew up in Yuma and the temp on the bank clocks would be 105 at midnight in the middle of summer. We always wondered what the heck these multi-weights were for.

Now I live in CT and its -15 wind chill outside. NOW I understand.

JohnnyO · Mar 11, 2005

I think the clearances on modern engines are too tight to use a straight 30 or 40 weight. Okay for the lawnmower or maybe a diesel but that's all. My .02.

dustyjoe1 · Mar 11, 2005

Lots of pickups still use it down here. They seem to run forever on 30 or 40. I got a buddy with an f150 that is upwards of 350,000 miles on Havoline 30. I wouldn't use it up north though, engines tend to complain while waiting for the oil to arrive.

Nothing wrong with it in hot weather.

cheers

Jimbo · Mar 11, 2005

At least as late as 1994, GM was still allowing straight 30 in light duty gasoline engines at temperatures above 50F, per the owners manual. Since that 4.3 V-6 had abnormally high oil consumption on 10W-30, I used straight 30 in the summer.

Drew99GT · Mar 11, 2005

quote:

Originally posted by dustyjoe1:
Lots of pickups still use it down here. They seem to run forever on 30 or 40. I got a buddy with an f150 that is upwards of 350,000 miles on Havoline 30. I wouldn't use it up north though, engines tend to complain while waiting for the oil to arrive.

Nothing wrong with it in hot weather.

cheers

Somethins wrong here. Those motors should be dead! They weren't getting proper cold start oil flow that the proper 0w-20 would give you in hot summer Texas weather

ediamiam · Mar 11, 2005

quote:

Originally posted by Audi Junkie:
I cannot get Delo 10w-30 but SAE 30 is available. Too bad it says not for EGR-equipped vehicles.

That's interesting. I have a gallon of Delo 400 in 30 wt, cf/sl rated. No verbiage on it indicating not for for EGR-equipped vehicles.

Using straight SAE 30 or 40 wt. in a modern engine...

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